1. Field of the Invention
The present invention relates to a material for removing offensive odors such as, for example, a deodorizer effective in removing offensive odors of ammonia, hydrogen sulfide, acetaldehyde, etc. originating from industrial and automotive exhaust gasses, and other smells of tobacco, human body, human waste, foods in refrigerators, etc. encountered in daily life, or an adsorbent for treating such gaseous substances, etc.
2. Description of the Related Art
Offensive odors from human activities in automobiles, kitchens, living rooms, offices, etc. include various mixed offensive odors. For instance, it is said that offensive odors in a car contain thousands of components originating from cigarette smoke, sweat, exhaust gas, dust, etc. The Offensive Odor Control Law (Japanese law) describes the following twelve malodorous components as especially important, namely, ammonia, methyl mercaptan, hydrogen sulfide, methylsulfide, methyl disulfide, trimethylamine, acetaldehyde, styrene, propionic acid, n-butyric acid, n-valeric acid, and iso-valeric acid.
The conventional methods of removing such offensive odors are by masking with an aromatic or by adsorption with activated carbon, silica gel, etc.
However, these methods have disadvantages. Masking with an aromatic does not remove the components of offensive odors in itself, and there may be an instance where the aromatic itself smells unpleasant. As to the physical adsorption by the adsorbents such as activated carbon, silica gel, etc., the kinds of malodorous components are limited depending on adsorbents to be used. For example, activated carbon is not effective at all for odors originating from such basic substances as ammonia, trimethylamine, etc.
To overcome the drawbacks, a chemical removing method has been proposed. It removes offensive odors by chemical neutralization. It permits the removal of both acid odors of acetaldehyde, hydrogen sulfide, etc. and basic odors of ammonia, trimethylamine, etc. More precisely, acid odors and basic odors are removed by neutralization with a basic adsorbent and an acid adsorbent, respectively.
However, such chemical adsorbents have also a disadvantage that the basic adsorbent and the acid adsorbent react with each other and become deactivated because of their properties, when they are supported on the same carrier or dispersed in the same liquid simultaneously.
Under the situation, the present inventors found a composite adsorbent which adsorbs and removes both acid odors and basic odors and which comprises an acid salt of an aromatic amino acid, an acid, and a transition metal compound, iodine or an iodine compound as active ingredients (Japanese Patent Application Laid-Open Nos. 3-296434 and 5-23588).
Of components of offensive odors, aldehydes such as acetaldehyde, etc. are the most evil-smelling. In particular, it has become important to remove aldehydes from high-humidity places such as living rooms and cars in the rainy season or in rainy days.
The above-mentioned composite adsorbent developed by the present inventors may adsorb and remove both acid odors and basic odors, but it has been found that the adsorbent is still unsatisfactory for adsorbing and removing aldehydes under the above-mentioned high-humidity condition.